The key difference between acetic acid and acetate is that acetic acid is a neutral, weak organic acid, whereas acetate is its conjugate base, carrying a negative charge (–1). Understanding the Difference Between Acetic Acid and Acetate is essential in chemistry, biochemistry, food technology, and environmental science because both forms play important roles in acidity, buffering, and biological reactions.
Overview and Key Difference
Acetic acid and acetate are closely related chemical species found in vinegar, metabolic pathways, industrial solvents, and biological buffering systems.
- Acetic acid (CH₃COOH) is the protonated, neutral form.
- Acetate (CH₃COO⁻) forms when acetic acid loses a proton (H⁺).
Because of this proton loss, acetate shifts from a neutral molecule to a negatively charged anion. This determines their behavior in water, pH-dependent reactions, and applications in real-world industries.
What is Acetic Acid?
Acetic acid, also known by its IUPAC name ethanoic acid, is an organic acid with the formula CH₃COOH and a molar mass of 60 g/mol.
Properties of Acetic Acid
- State: Colorless liquid at room temperature
- Taste & Odor: Sour taste; strong, vinegar-like pungent smell
- Acidity: Weak acid (partially dissociates in water)
- Functional Group: Contains a carboxyl group (–COOH)
- pKa: Approximately 4.76
- Boiling Point: 118°C
- Melting Point: 16.6°C
Glacial Acetic Acid
The concentrated, water-free form of acetic acid (≥99%) is known as glacial acetic acid.
- Highly corrosive
- Causes skin burns
- Used in chemical synthesis and lab preparations
Molecular Behavior
- Forms hydrogen-bonded dimers in vapor phase
- In solid form, molecules form hydrogen-bonded chains
- Miscible with water, ethanol, acetone, and many polar/non-polar solvents
Applications of Acetic Acid
- Food industry (vinegar production ~4–8% acetic acid)
- Manufacture of polymers (e.g., cellulose acetate)
- Chemical synthesis (acetic anhydride, esters)
- Medical use (antibacterial properties; ear infection treatment)
- Textile dyeing and printing
What is Acetate?
Acetate (CH₃COO⁻) is the anionic form of acetic acid, created when the acid loses a proton (H⁺) from its carboxyl group. It has a molar mass of 59 g/mol and a formal negative charge.
Where Acetate Exists
Because it carries a charge, acetate rarely exists alone. Instead, it forms salts or compounds, such as:
- Sodium acetate (CH₃COONa)
- Potassium acetate (CH₃COOK)
- Ammonium acetate (CH₃COONH₄)
- Calcium acetate (Ca(CH₃COO)₂)
pH Behavior
- Below pH 4.76: Acetic acid dominates
- Above pH 5.5: Acetate becomes the stable form
Applications of Acetate
- Widely used as a biochemical buffer component
- Sodium acetate is used in heating pads (supersaturated solution crystallization)
- Calcium acetate used in medicines to reduce phosphate levels
- Used in the textile, leather, and photography industries
- Part of metabolic pathways (e.g., acetyl-CoA production)
Acetic Acid vs Acetate – Comparison Table
| Property | Acetic Acid (CH₃COOH) | Acetate (CH₃COO⁻) |
| Nature | Neutral organic acid | Negatively charged anion |
| Molar Mass | 60 g/mol | 59 g/mol |
| Charge | Zero | –1 |
| Chemical Category | Carboxylic acid | Conjugate base / carboxylate |
| pH Stability | More stable in acidic conditions (low pH ~5) | More stable in basic conditions (pH > 5.5) |
| Solubility | Highly soluble in water and alcohol | Exists mostly as salts; highly soluble |
| Taste & Odor | Sour, vinegar-like | Odorless (in salt form) |
| Uses | Vinegar, chemicals, pharmaceuticals | Buffers, salts, medicine, industry |
| Reactivity | Weak acid; partially dissociates | Base-like behavior; participates in ionic reactions |
Summary
Acetic acid and acetate are chemically connected but dramatically different in charge, reactivity, and behavior. Acetic acid is a neutral weak acid, while acetate is its deprotonated, negatively charged anion. Understanding the Difference Between Acetic Acid and Acetate helps in predicting their behavior in pH changes, buffer formation, biological functions, and industrial applications.
In simple terms:
- Acetic acid = protonated (neutral) form
- Acetate = deprotonated (charged) form
Both play crucial roles in chemistry, biochemistry, and everyday products like vinegar, medicines, polymers, and industrial chemicals.
Reference:
1. “Acetic Acid.” Wikipedia, 18 Apr. 2018,
2. “Acetic Acid.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine,
3. “Acetate.” Wikipedia, 10 Apr. 2018,